The long range goal is to understand the changes in protein metabolism that occur with menopause. Aging itself is marked with a decline in lean body or fat free mass and a gain in fat mass. Menopause induces a further increased loss of FFM,largely from skeletal muscle. The key element to menopause is the loss of ovarian hormone production,which is treated by estrogen and progestin hormone replacement therapy. We hypothesize thet the loss of ovarian hormone production in menopause reduces protein synthesis in muscle,which increases loss of muscle mass over time and the HRT will attenuate this reduction in protein synthesis and muscle mass loss.